The present invention relates to piering systems and in particular to a concentrically loaded, adjustable, steel pipe foundation repair piering system.
In many areas of the United States building foundations rest on unstable soil. Changes in local condition cause soil movement and damage to the building. Piering systems are used in such areas to provide support from bedrock under the buildings. Known piering systems include piers sunk below the foundation to a stable surface, for example, bedrock. The pier system reaches up to the foundation to provide vertical support. Unfortunately, the bottom of the foundation may not provide a horizontal surface for the support to push against and movement of the foundation may result in the foundation breaking away from the support.
Further, concentrically loaded piering systems (those installed directly under the wall being supported or lifted, as opposed to being attached to the outer edge of the foundation footing) typically are easy to break with offset loads created by imperfect installation, and have loose adjusting components (“shims”) that can fall off if the structure moves after installation. Piers installed directly under the wall must be installed in very short “segments”. The link between the segments must be very strong to prevent breakage.
Known piering systems typically require a number of loose adjusting components (or shims) which may fall off if the structure “heaves” or moves after installation. As a result, the piering system may require adjusting after a minor soil movement due to the lost shims even if the foundation returns to the original position.
A need thus remains for an improved piering system which remains attached to the building foundation and can tolerate sloped foundation bottom surfaces.